Method for producing iron oxyhydroxide particle

Abstract

First, a ferrous iron-containing suspension solution is obtained by mixing an aqueous ferrous salt solution and an aqueous alkali solution containing one or two of an alkali carbonate and an alkali hydroxide. Then, an iron oxyhydroxide particle precursor is obtained by blowing an oxygen-containing gas having an oxygen component proportion of 0.5 to 0.8 into the suspension solution thus obtained to oxidize the ferrous iron in the suspension solution at an oxidation rate of 30 to 65% while the suspension solution is being controlled to fall in a temperature range of −5° C. or higher and lower than 10° C. Thereafter, the iron oxyhydroxide particles 2 are produced from the iron oxyhydroxide particle precursor by blowing an oxygen-containing gas into the suspension solution containing the iron oxyhydroxide particle precursor while the suspension solution is being controlled to fall in a temperature range of 20° C. or higher and lower than 45° C.

1 . A method for producing an iron oxyhydroxide particle, the method comprising:
 a step A of obtaining a ferrous iron-containing suspension solution by mixing an aqueous ferrous salt solution and an aqueous alkali solution containing one or two of an alkali carbonate and an alkali hydroxide;   a step B of obtaining an iron oxyhydroxide particle precursor by blowing an oxygen-containing gas having an oxygen component proportion of 0.5 to 0.8 into the suspension solution obtained in the step A to oxidize the ferrous iron in the suspension solution at an oxidation rate of 30 to 65% while the suspension solution is being controlled to fall in a temperature range of −5° C. or higher and lower than 10° C.; and   a step C of producing iron oxyhydroxide particles from the iron oxyhydroxide particle precursor, after the step B, by blowing an oxygen-containing gas into the suspension solution containing the iron oxyhydroxide particle precursor while the suspension solution is being controlled to fall in a temperature range of 20° C. or higher and lower than 45° C.   
     
     
         2 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein in the step A, the concentration of Fe in the ferrous iron-containing suspension solution is 0.001 to 0.1 mol/L. 
     
     
         3 . The method for producing an iron oxyhydroxide particle according to  claim 2 , wherein the concentration of Fe is 0.05 mol/L or less. 
     
     
         4 . The method for producing an iron oxyhydroxide particle according to  claim 2 , wherein the concentration of Fe is 0.01 mol/L or more. 
     
     
         5 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein in the step A, the hydrogen ion index pH of the aqueous alkali solution is 9 to 11. 
     
     
         6 . The method for producing an iron oxyhydroxide particle according to  claim 5 , wherein the hydrogen ion index pH of the aqueous alkali solution is 9.5 to 10.5. 
     
     
         7 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein the step A is performed in an airtight vessel in which the atmosphere is set to be nonoxidative. 
     
     
         8 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein in the step B, the diameter of the gas bubble in the oxygen-containing gas is 0.5 mm or more and less than 2.0 mm. 
     
     
         9 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein in the step B, the ferrous iron is oxidized at an oxidation rate of 35 to 50%. 
     
     
         10 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein the aqueous ferrous salt solution is an aqueous iron sulfate solution. 
     
     
         11 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein sodium hydrogen carbonate is used as the alkali carbonate. 
     
     
         12 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein sodium hydroxide is used as the alkali hydroxide. 
     
     
         13 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein in the step C, the oxygen component proportion in the oxygen-containing gas is 0.2 to 0.8. 
     
     
         14 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein in the step C, the oxygen-containing gas is blown into the suspension solution while the suspension solution is being controlled to fall in a temperature range of 25° C. or higher and lower than 35° C. 
     
     
         15 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein the iron oxyhydroxide particles obtained in the step C are needle-like or spindle-like. 
     
     
         16 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein the iron oxyhydroxide particles obtained in the step C are 20 to 50 nm in mean long axis length and 3 to 10 in aspect ratio. 
     
     
         17 . The method for producing an iron oxyhydroxide particle according to  claim 1 , wherein the iron oxyhydroxide particle precursor is GR1 that contains a carbonate ion and has a chemical formula [Fe 4   (II) Fe 2   (III) (OH) 12 ][CO 3 .2H 2 O] or GR2 that contains a sulfate ion and has a chemical formula [Fe 4   (II) Fe 2   (III) (OH) 12 ][SO 4 .2H 2 O]. 
     
     
         18 . The method for producing an iron oxyhydroxide particle according to  claim 1 , further comprising a step D of subjecting, after the step C, the iron oxyhydroxide particles to a reduction treatment to be converted into metal magnetic particles. 
     
     
         19 . The method for producing an iron oxyhydroxide particle according to  claim 18 , wherein the metal magnetic particles are needle-like.